Without any exceptions, all of the existing versions of the Coriolis force mass flowmeter on the convective inertia force flowmeter employ a combination of one or a pair of cunduits under a flexural vibration and two vibration sensors respectively detecting the flexural vibration of the conduit at two sections of the conduit, wherein the mass flow rate of fluid moving through the conduit is determined as a product of an empirically determined constant and a function of a phase difference between two alternating electrical signals respectively generated by the two vibration sensors. It can be readily shown by carrying out a reasonably simple mathematical analysis of the flexural vibration of a conduit containing fluid moving there-through that the above-mentioned empirically determined constant is not a constant in actuality and varies as a function of several dynamic variables such as the amplitude and frequency of the flexural vibration of the conduit, density of the fluid media, stiffness of the conduit, etc. As the existing versions of the Coriolis force or inertia force mass flowmeter operate on principles less than fully rigorous and accurate, these mass flowmeters lack the self-calibrating ability and, consequently, these mass flowmeters must be recalibrated time to time in order to eliminate the error in the mass flow measurement arising from the change in the dynamic variable characterizing the flexural vibration of the conduit containing the moving fluid therethrough.
Another short-coming of the existing versions of the Coriolis force or inertia force mass flowmeter is their vulnerability to ambient mechanical vibrations and their inability to measure the mass flow rate of media having low values of density such as gaseous media, which short-coming results from the fact that the existing versions of the Coriolis force or convective inertia force mass flowmeter measures the flexural vibration of the conduit at two different sections thereof and measures a phase difference between the two flexural vibrations of the conduit respectively measured at the two different sections of the conduit. It is readily realized that the phase difference between the two flexural vibration of the conduit respectively occurring at the two different sections of the conduit is a result of the phase difference between two transverse pressure gradients respectively existing at the two different sections of the conduit and, consequently, it is greatly more advantageous to measure the two transverse pressure gradients respectively existing at the two different sections of the conduit rather than measuring the flexural vibration of the conduit at the two different sections of the conduit, and determine the mass flow rate of fluid as a function of the phase difference between the two transverse pressure gradients instead of the phase difference between the two flexural vibrations. The present invention teaches a new method and structural embodiments for measuring directly the convective inertia force experienced by the fluid media moving through the conduit, wherein transverse pressure gradient existing in the fluid media is detected at two different sections of the conduit and the mass flow of the fluid media is determined as a function of a phase difference between the two transverse pressure gradients. As the inertia force flowmeter of the present invention detecting the transverse pressure gradients at two different sections of the conduit and obtaining the phase difference between the two transverse pressure gradients as a measure of mass flow rate of fluid media measures the convective inertia force experienced by the fluid media directly instead of measuring an effect of the convective inertia force in the form of the resulting flexible vibration of the conduit, the present invention provides a new inertia force mass flowmeter calibrating itself on a real time basis and capable of measuring mass flow rate of liquid media as well as gaseous media, which new inertia force mass flowmeter can be constructed in all different sizes varing from a very small size to a very large size, and can be made of a rigid curved pipe or pipes with thick wall.